Noted architect/designer Oxman made a trip to Paris last weekend to see her activist investor beau Ackman compete in the Finance Cup — the tennis tournament in which former pro and top college players working full-time in finance face off.

We hear alluring Oxman sat courtside cheering on her boyfriend, and that the pair seemed very much in love. The two were openly affectionate and later attended a party for the tournament as a couple.

Neri OxmanPatrick McMullan

Joked one source, “Bill won his match, and has won the girl. Brad Pitt will need to up his tennis game — and his educational degrees — if he wants such a super impressive, and highly intellectual woman.”

Ackman played in a doubles match with US teammate Jonathan Canter, once ranked No. 36 in the world. (Ackman and Canter beat a strong team of former Italian juniors doubles champ Alfredo Caturano and former pro Rupert de Laszlo.)

We hear there’s usually a heated rivalry between Ackman and Europe’s biggest activist investor, Swedish billionaire Christer Gardell — whose firm counts Carl Icahn as an investor. But this year Gardell was beaten by Jeffrey Appel, the investment banker/tennis player known as the “Mayor of New York Tennis” who captains the US squad. The US won the heated rivalry that coincided with the French Open this year, nine matches to four, and has taken three of four annual cups.

Sniffed one European participant of Ackman’s game, “Bill is impressively good for a guy who didn’t even play tennis at university … but let’s just say his plane is more valuable to the US team than his backhand.”

Either way, Oxman was by his side at a party later at L’Arc, where she cheerfully posed for pics with Ackman, Gardell, Appel and further guests Walter Dolhare of Wells Fargo Securities, Deutsche Bank’s Jan Olssen, HSBC Nordic Private Banking head Tobias Hildebrand and Agnes Bradbury of the Bradbury Group at Keller Williams.

Also on the court playing right behind Ackman for the US were former world No. 1 doubles players Alex O’Brien and Richey Reneberg. David Anving captained the Euro squad, and players on both sides also hailed from firms including Goldman Sachs, Barclays, JP Morgan and Merrill Lynch.

A rep for Ackman didn’t comment, and busy Oxman didn’t get back to us.

Ackman’s nuts about his tennis, even building his own private court on top of his new Manhattan office.

A source told us in April of Pitt and Oxman: “Brad and Neri instantly hit it off because they share the same passion for architecture, design and art. This is best described as a professional friendship,” but “Brad is very interested in spending more time with Neri, she is fascinating.”